8

如何根据子网掩码测试两个IP是否在同一个网络中?

例如,我有 IP 1.2.3.4 和 1.2.4.3:如果掩码为 255.0.0.0 或 255.255.0.0 甚至 255.255.248.0,则两者都在同一个网络中,但如果掩码为 255.255.255.0..

4

3 回答 3

14

试试这个方法:

public static boolean sameNetwork(String ip1, String ip2, String mask) 
throws Exception {

    byte[] a1 = InetAddress.getByName(ip1).getAddress();
    byte[] a2 = InetAddress.getByName(ip2).getAddress();
    byte[] m = InetAddress.getByName(mask).getAddress();

    for (int i = 0; i < a1.length; i++)
        if ((a1[i] & m[i]) != (a2[i] & m[i]))
            return false;

    return true;

}

并像这样使用它:

sameNetwork("1.2.3.4", "1.2.4.3", "255.255.255.0")
> false

编辑 :

如果您已经将 IP 作为InetAddress对象:

public static boolean sameNetwork(InetAddress ip1, InetAddress ip2, String mask) 
throws Exception {

    byte[] a1 = ip1.getAddress();
    byte[] a2 = ip2.getAddress();
    byte[] m = InetAddress.getByName(mask).getAddress();

    for (int i = 0; i < a1.length; i++)
        if ((a1[i] & m[i]) != (a2[i] & m[i]))
            return false;

    return true;

}
于 2011-12-19T00:15:14.983 回答
5

很简单:mask & ip1 == mask & ip2-您必须将 IP 全部解释为一个数字,但这应该很明显。

于 2011-12-19T00:04:52.310 回答
0

此解决方案也适用于 IPv4/IPv6。

static boolean sameNetwork(final byte[] x, final byte[] y, final int mask) {
    if(x == y) return true;
    if(x == null || y == null) return false;
    if(x.length != y.length) return false;
    final int bits  = mask &   7;
    final int bytes = mask >>> 3;
    for(int i=0;i<bytes;i++)  if(x[i] != y[i]) return false;
    final int shift = 8 - bits;
    if(bits != 0 && x[bytes]>>>shift != y[bytes]>>>shift) return false;
    return true;
}
static boolean sameNetwork(final InetAddress a, final InetAddress b, final int mask) {
    return sameNetwork(a.getAddress(), b.getAddress(), mask);
}
于 2015-04-07T23:12:34.760 回答